Isbn

4 lettersnounrare

Updated February 2026

Definition

International Standard Book Number, a unique identifier for books.

“Every published book has an ISBN.”

🟩

Acronym unlikely to appear in Wordle.

🔤

Worth 6 points but may not be accepted as valid.

Look up isbn in an authoritative dictionary for full definitions, pronunciation, and etymology.

Download Word Challenge and challenge yourself with our daily word puzzles. Guess the hidden word in six tries or fewer!